Slotted waveguide antenna stiffened structure (SWASS) integrates the slotted waveguide antennas (SWAs) into the carbon fiber reinforced polymer (CFRP) composites in airplane skins. SWASS utilizes conventional half-wavelength rectangular slots as elements of the SWA array. Size of the rectangular slots is an important factor affecting the mechanical performance of the SWASS and restricting its application. Subwavelength spiral slots are recently proposed to replace the rectangular slots and consequently improve the SWASS mechanical performance. In this paper, a four element array using subwavelength spiral slots is presented which demonstrates the feasibility of using such slots for SWASS application.